This invention relates to a tilt locking system for boat propellers and more particularly to an improved tilt locking and shock absorbing arrangement for a marine outboard drive.
It has been known in the mounting of marine outboard drives, such as the outboard drive unit of an inboard/outboard arrangement or in an outboard motor per se, to employ a hydraulic shock absorbing arrangement between the outboard drive and the boat hull. The shock absorbing arrangement normally is operative to permit the outboard drive to pop up when an underwater obstacle is struck and to gradually return to its normal trim position. Frequently, however, it is desirable to adjust the trim angle of the outboard drive so as to permit operation is shallow water without interference from the hydraulic arrangement. It is particularly desirable if the shock absorbing arrangement is also functional when the outboard drive is operated in its shallow trim position. That is, the arrangement should be such that the motor is permitted to pop up even when operating in its shallow water condition but will be returned to its operating position once the underwater obstacle has been passed. In my copending application, Ser. No. 481,315, filed Apr. 1, 1983, entitled "Tilt Locking System For Ship Propellers" and assigned to the assignee of this invention, there is disclosed an improved and simplified hydraulic arrangement that achieves these functions. Although the arrangement shown in that patent application achieves these functions, it requires the use of a plurality of hydraulic circuits that extend between the two chambers of the shock absorbing mechanism and which embody check valves, manually operated valves and time delay valves. Although effective, the system is therefore complicated, and accordingly, expensive and relatively large in size.
It is, therefore, a principal object of this invention to provide an improved tilt locking system for an outboard drive that permits the outboard drive to pop up and return from a normal trim condition or from a shallow trim condition.
It is a further object of this invention to provide an improved and simplified tilt locking mechanism of the type described.
In my aforedescribed patent application, the hydraulic circuit includes a first passage that extends from one chamber of the hydraulic mechanism to another chamber and that permits flow from the first chamber to the second chamber through a check valve and a manually operated valve. A second passage extends between the chambers and includes a second check valve and a second manually operated valve that permit flow selectively from the second chamber to the first chamber. Although such an arrangement permits the achievement of the functions set forth above, it is, as has also been noted, complicated.
It is, therefore, a still further object of this invention to provide a hydraulic circuitry for a tilt locking mechanism of an outboard drive wherein flow is selectively permitted between the chambers in either direction through a simplified and improved control mechanism.